(info, html): Implement.

(all): Depend on info.

Flatten info directory.  This undoes the move to one subdirectory per
chapter, which was done during Empire 2.  The structure doesn't buy us
much, as the info name space is flat, and it complicates makefiles.

Overhaul info.pl:
- It now wants to run in the root of the build tree.
- Information on source files and subjects is now stored in makefiles,
  thus info.pl no longer picks up random junk from the file system.
- Clean up Perl anachronisms, in particular use subroutine arguments and
  results rather than global variables where convenient.
- Change format of diagnostics to the common format used by GNU tools,
  so that Emacs and the like can parse it.
- Catch missing .SA.
- When creating a new subject file, cowardly refuse to overwrite an
  existing file.
- Subject files contain topics sorted by chapter, then by name.  The
  order of chapters used to depend on how Perl sorts hash keys.  Fix
  it.

info/retreat.t

@@ -0,0 +1,92 @@
+.TH Command RETREAT
+.NA retreat "Set retreat conditions/paths for ships or fleets"
+.LV Expert
+.SY "retreat [<SHIP/FLEET> | <SECTS>] [<PATH>] [<CONDITIONS>]"
+.SY "lretreat [<UNIT/ARMY> | <SECTS>] [<PATH>] [<CONDITIONS>]"
+The retreat command allows you to examine or modify the retreat 
+paths and conditions of your ships or units. The following description
+is for ships. Land units are exactly the same, except of course that
+some of the retreat conditions (being sonared, depth charged, etc) don't apply.
+.s1
+The <SHIP/FLEET> and <SECTS> arguments are provided to specify which
+ships to view or give orders for. If a fleet designation is given when
+specifying orders, the orders apply to all ships within that fleet.
+.s1
+Retreat expects an argument.  To see every ship you own, give it
+the argument '*', or type "retreat *".
+.s1
+The report format contains the following fields:
+.s1
+.in \w'shiptype\0\0'u
+.L shp#
+the ship number
+.L shiptype
+the type of ship; \*Qpatrol boat\*U, \*Qsubmarine\*U, etc,
+.L x,y
+the ship's current location (relative to your capital),
+.L flt
+the fleet designation letter (set by \*Qfleetadd\*U command),
+.L path
+the ship's current retreat path.
+.L as_flt?
+whether or not the ship's retreat path is a fleet retreat path
+.L flags
+what conditions the ship will retreat under
+.in
+.s1
+For example:
+.EX retreat *
+.NF
+shp#     ship type       x,y   fl path       as flt? flags
+   0 battleship 4        2,0      jjuuj              I
+1 ship
+.FI
+.s1
+.L Overview
+.s1
+A player may give retreat orders for a ship or a fleet. Retreat 
+orders include a set of conditions that determine when the fleet/ship
+will retreat, and a path that the fleet/ship will follow. When a condition
+is met for a particular ship, the \*Qas flt?\*U field is checked. If it
+is Yes, then every ship in that fleet with fleet retreat orders retreats
+along the specified path. If it is no, then the retreat orders apply to 
+that ship only, and only that ship retreats.
+.s1
+When a ship is added to a fleet, it is given the retreat orders of the
+first ship in that fleet that has fleet retreat orders and is in the
+same sector, if any exist.
+.s1
+Retreat orders are wiped when a ship navigates.
+.s1
+Retreat conditions at present include:
+.nf
+
+		Condition	Meaning
+		I		Retreat when the ship is injured,
+				i.e. whenever the ship is damaged
+				by fire, bombs, or torping.
+		T		Retreat when a sub torpedos or tries
+				to torpedo the ship.
+		B		Retreat when a plane bombs or tries
+				to bomb the ship.
+		S		Retreat when the ship detects a sonar
+				ping.
+		D		Retreat when the ship is depth-charged.
+		H		Retreat when helpless. A ship is helpless
+				when it is fired upon, and no friendly
+				ships/sectors (including the ship itself)
+				are able to fire back at the aggressor.
+                U               Retreat upon a failed boarding attempt.
+		C		Clear the flags
+.fi
+.s1
+For example, if the battleship above was fired at, it would attempt to
+retreat 2 sectors, jj, using the normal amount of mobility for moving
+2 sectors. It would then look like:
+.NF
+shp#     ship type       x,y   fl path       as flt? flags
+   0 battleship 4        2,0      uuj                I
+1 ship
+.FI
+.s1
+.SA "ship, fleetadd, Ships"